As an example of the conventional power transmitting mechanism FIGS. 4 and 5 of the British Patent GB2269440 show a torque fluctuation absorbing device. Referring to FIGS. 4 and 5, the torque fluctuation absorbing device provided for absorbing torque fluctuations between an engine and a transmission includes driving members 53, 54, 60, driven members 55, 56, 59, a coil spring 50 as a torsion mechanism and a hysteresis mechanism 62 provided between lateral sides of the driving member (driving plate) 53 and the driven member (driven plate) 56 for exhibiting hysteresis by frictional sliding. The driving power from the engine is transmitted from the driving member 60 via 53, 54, coil spring 50 and driven member 55 to 56 and 59. A roller bearing 61 is mounted between the outer periphery of the driving member 60 and the inner periphery of the driven member 59 for holding the driven member (flywheel) 59 concentrically and for free relative rotation with respect to the driving member (inner hub) 60.
A torque fluctuation absorbing device having a flange-shaped slide bearing inserted radially between the driving member and the driven member, as a bearing provided between the outer periphery of the driving member and the inner periphery of the driven member for holding the driven member concentrically and for free relative rotation with respect to the driving member, is proposed in JP Patent Publication JP-B-56-43176. This slide bearing has slide surfaces on both the the outer periphery of the driving member and the inner periphery of the driven member.
In the torque fluctuation device of GB2269440, a grease is sealed in a spacing holding a torsion spring 50 installed as a torsion member on the outer periphery of the device. As a seal on the inner periphery of the spacing, a seal 58 and a thin spring plate in the compressed state are arranged axially between the inner peripheral portion of the driven plate 56 and the inner peripheral portion of the driving plate 54 for allowing for relative rotation between the driving plate 54 and the driven plate 56 and for displaying the sealing function.
Also, in the device of GB2269440, a driving member (driving plate) 53 is formed of iron for reducing the cost.
Referring to FIG. 4 showing the device of GB2269440, the outer peripheral sides of spring sheets 51, 52 are extended between the outer peripheral side of the torsion spring 50 and the inner periphery of the driving side plates 53, 54, on the outer peripheral side of the torsion spring 50 and on the inner peripheral sides of the driving plates 53, 54, for preventing the torsion spring 50 from being moved under centrifugal force towards the outer periphery to come into sliding contact with the driving plates 53, 54.